An email making the rounds hit David Passell's inbox. David wonders if anyone else with a iMac or MacBook with an ATI X1600 GPU is having these types of problems. A list of links on Apple Forums discussing this situation is listed below, in the event you are concerned.
The problem is described by an Australian long-time Mac enthusiast: "I am a long-time Mac enthusiast who feels a bit more "down under" than usual. I have spoken to the Australian Apple Support regarding my white Intel iMac which has had issues with the graphics card/logic board since three months (!) out of factory warranty. I purchased the machine, which had been used very little, from a friend (a fellow Mac User Group member for many years) in February 2008. It was then two months out of warranty. When I realized he hadn't taken out Apple Care I called Apple and was told that to take out Apple Care it had to be done within the original 12 months warranty period. The machine was however as new with relatively few hours of operation and nothing more intensive than web browsing and emails so I thought I'd be alright.
"The very next month, thin horizontal multicolored lines started appearing sporadically on my screen. I called support who said my warranty had expired and there were no known issues with my model so I was on my own. I repaired permissions and scanned the disk for problems but short of some incorrect permissions on occasion no problem was found. Gradually the problem worsened and the computer would sometimes freeze and the screen change to a pattern of multicolored vertical lines.
In November 2008 I actually took a photo of the screen on such a freeze using my iPhone and I have done so also on another occasion. I have attached links to the pics. I have taken the iMac to my local service agent and they cleaned it and ran tests which failed to find a cause for the problems. They suggested it may be the graphics module which is part of the logic board and can't be replaced.
The problem has now become so bad that I have had to change the background to a plain color and and turn off screensavers and anything graphic intensive. I am now down to one or two freezes & reboots per day from four to five." This email was sent by Mikael Lindstedt.
Links:
http://discussions.apple.com/thread.jspa?threadID=1516765&start=0&tstart=0
http://discussions.apple.com/thread.jspa?threadID=1467276&tstart=0
http://discussions.apple.com/thread.jspa?threadID=2136365&start=0&tstart=0
http://discussions.apple.com/thread.jspa?threadID=2181088
http://discussions.apple.com/thread.jspa?threadID=1697470&start=0&tstart=0
http://discussions.apple.com/thread.jspa?threadID=1974295&start=0&tstart=0
http://discussions.apple.com/thread.jspa?threadID=2194641
http://discussions.apple.com/thread.jspa?threadID=1878407&tstart=0
http://discussions.apple.com/thread.jspa?threadID=2109263
http://discussions.apple.com/thread.jspa?threadID=1726184&start=0&tstart=0
http://discussions.apple.com/thread.jspa?threadID=2147082
http://discussions.apple.com/thread.jspa?threadID=1609243&start=0&tstart=0
http://discussions.apple.com/thread.jspa?messageID=10473645�
http://discussions.apple.com/thread.jspa?threadID=2165038
http://discussions.apple.com/thread.jspa?threadID=1974295
http://discussions.apple.com/thread.jspa?threadID=1995151&start=0&tstart=0
Screen pics:
http://img200.imageshack.us/gal.php?g=attachmentpe.jpg
http://img21.imageshack.us/g/img0073hw.jpg/
Non-Apple links:
http://getsatisfaction.com/apple/topics/2006_imac_graphics_card_crash_freeze
http://torley.com/macbook-pro-with-ati-radeon-x1600-distorted-video-glitches
http://www.petitionspot.com/petitions/imacrecall/
http://forums.macworld.com/index.php?/topic/114232-imac-lines-on-screen/
http://reviews.cnet.com/8301-13727_7-10330060-263.html?tag=mncol
http://www.sfmslaw.com/pages/cases.php?id=779